#include <iostream>
#include <memory>
#include <vector>

using namespace std;

class Shape {
public:
    virtual void draw() = 0;
    virtual ~Shape() = default;
};

class Square : public Shape {
public:
    virtual void draw() {
        cout << "Square" << endl;
    }
};

class Circle : public Shape {
public:
    virtual void draw() {
        cout << "Circle" << endl;
    }
};

// Both derived from shape, so that they can be treated as same
class ShapeGroup : public Shape {
    vector<shared_ptr<Shape>> shapes;
public:
    void add_shape(shared_ptr<Shape> item) {
        shapes.push_back(item);
    }

    virtual void draw() {
        cout << "draw group" << endl;
        for (auto item : shapes) {
            item->draw();
        }
    }
};


int main() {
    auto s1 = make_shared<Square>();
    auto s2 = make_shared<Square>();
    auto c1 = make_shared<Circle>();
    auto sg = make_shared<ShapeGroup>();

    sg->add_shape(s1);
    sg->add_shape(s2);
    sg->add_shape(c1);
    sg->draw();
}